This invention relates to a lubrication structure for lubrication in a casing of a transmission which stores a plurality of shafts and gears by hydraulic fluid pumped up by a rotation of a final gear for a final speed reduction gear.
As a lubrication structure provided by a transmission such as an automatic transmission installed on a vehicle, there is a lubrication structure disclosed in Japanese Laid Open Patent Application No. 2007-159314 (Patent Document 1). This lubrication structure is configured so that in a casing of a transmission which stores a plurality of shafts and gears, lubricating oil collected at the bottom of the casing can be pumped up by a differential gear (a final gear for a final speed reducer) and supplied to whatever to be lubricated such as other gears and bearings positioned upward in the casing.
Further, the above-mentioned transmission is provided with a breather structure for regulating temperature and pressure in the casing. This breather structure is configured to ventilate in the casing by providing a through-hole to the casing and a pipe (a breather-pipe) communicating to the outside. In this case, in the above-described breather structure, high-temperature and high-pressure oil might spout out outside the casing from the through-hole and the pipe, depending on conditions such as positions at and directions in which the through-hole and the pipe is arranged.
And, if in the casing of the transmission, the breather structure is arranged higher than the differential gear, the hydraulic fluid pumped up by the differential gear might be dispersed to the breather structure and a perimeter thereof. Therefore, as a counter measure to prevent that the hydraulic fluid would spout out from the through-hole and the pipe of the breather structure, a platy guide member (a baffle plate) can be considered to be installed in the casing for receiving and rectifying the hydraulic fluid pumped up by the differential gear.
However, if the guide member is newly installed, an installation space for such new component needs to be secured, which will necessitate to change a layout of components in the casing. In addition, it will necessitate to newly secure mounting positions (bolt holes and a boss section for installing them, etc.) for mounting to the casing fasteners such as bolts for fixing the guide member, which might necessitate to change a shape of the casing. Furthermore, an increase in number of parts might increase the transmission in weight and dimensions of the transmission and lead to complexity of manufacture process.